Canister

The APERS [anti-personnel] canister is a gun launched ammunition (round). It may be fired from, for example, a tank or artillery piece. The canister is designed for defeating groups of personnel at various ranges, as opposed to defeating tanks, armored personnel carriers, aircraft, or other vehicle targets. The goal of this type of ammunition, much like a shotgun, is to disperse the payload upon exiting the gun tube and achieve maximum dispersion thus eliminating the maximum number of enemy personnel. As with a shrapnel round, the payload may comprise round tungsten balls, steel rectangular prisms, or flechettes. The cannister round differs from a shrapnel round in that the later is a long range munition that has a bursting charge that detonates in proximity to the target, while the former is a short range spontaneously disperses the chargo at the moment of exiting the gun tube.

Effective close-in support of men and material is a mandatory requirement for modern gun systems. Recent advances in medium caliber, i.e., 20 to 30mm ammunition designs have brought about significant improvements towards this end. For instance, controlled fragmentation high explosive rounds, and multiple flechette rounds have greatly increased the survivability of the modern armed vehicle against ambush. However, these munitions have their limitations.

It was discovered early, in the use of cannon and artillery pieces, that they were no defense against close-up charge of troops. Thus the expedients of the so-called "grape-shot" and the like were developed, wherein a large number of fragments of various forms or shapes were loaded in the weapon and fired at point blank range. This principle was extended further with the development of modern cannister ammunition wherein a shell body was designed specifically for containing a multiplicity of fragments and adapted for firing at point blank range. The ammunition is designed to open substantially immediately after exit from the muzzle of the weapon. The cannister round is the antipersonnel round that essentially bursts at the muzzle.

As is well known in the art, the fragments will disperse in relation to the twist of the rifling in the weapon. Since this ammunition functioned substantially at the muzzle of the weapon its beneficial anti-personnel effect could not be utilized at ranges other than essentially point blank. The cannister round is effective from 250 to 500 meters. In the 19th Century, at extremely close ranges of 200 yards or less, artillerymen often loaded double charges of canister.

Prior to the 20th Century field artillery firing was by "direct fire," that is, fire in which the target is in view of the gun. The use of canister artillery rounds was reported as early as the year 1410. Field Artillery guns in the 18th Century were small, with a short range. Solid shot and grape were alone used; explosive shell and shrapnel had not been invented. Canister consisted of a tin cylinder in which was packed a number of iron or lead balls. Upon discharge the cylinder split open and the smaller projectiles fanned out. Canister was an extremely effective antipersonnel weapon, with an effective range of 400 yards. In emergencies double loads of canister could be used at ranges less than 200 yards, using a single propelling charge. One Grape Shot round fired by 19th century Artillery against the advance of Infantry was made up of 36 large metal balls. Once fired, the balls are thrown free, each taking its own path.

The range of smoothbore cannon gradually increased over the years until, by the Napoleonic era, cannon could fire about 300 yards, or about the range of the Roman ballistae. Up until the Crimean War (1854), 70 percent of all cannon shot fired was solid ball shot. But as early as the 1740s artillery gunners had various types of artillery rounds at their disposal. Heavy rounds that exploded on contact were used primarily by howitzers while artillery guns, those with a flatter trajectory, commonly used canister, chain, and grapeshot against cavalry and infantry formations.

An 1856 handbook noted that the canister is broken by the shock of the exploded charge in the piece, and the balls spread themselves out in front of the muzzle in the shape of a cone. They strike the object partly directly, partly by ricochet. As the number of balls which issue from the piece is very considerable, and as, in consequence of their diminutive size, they easily stick or lose their force, when the ground is soft or uneven, it is obvious that the effect of this nature of fire is more dependent upon the nature of the ground than any other. It is only firm even ground which gives good effect, while, on the other hand, meadows, freshly ploughed fields, ditches, ledges of earth, tall tubers, and even fields of corn considerably diminish the effect of this fire. The large balls of the 12-pounder overcome the obstacles of the ground easier than do those of the 6-pounder; the heavier calibre is superior to the lighter by an average of about 200 paces.

Canister shot may be used against the enemy's artillery in the last stages of an attack, in order to put their men and horses hors de combat; it is particularly effective when it can be thrown in on the flank of an enemy's battery. Against field entrenchments, villages, and skirts of woods a lively canister shot fire should precede the storming columns of the infantry. To prevent a thick swarm of tirailleurs from penetrating into the battery it is often the last resort, when musketry fire is incapable of doing so.

Canister shot fire is more equally and surely effective than shrapnell fire ; especially in quick firing and when the object is in motion. It is always to be preferred to shrapnell fire in the defence of a battery, when the attacks of the enemy's troops are to be beaten off. Under 600 paces it is annihilating, and decides the fray in a few minutes ; at greater distances, on the other hand, it may in unfavourable ground be ineffective ; it is, therefore, to the interest of the artillery not to deprive themselves of this last decisive measure, by making use of that nature of fire too early ; for an unprofitable canister shot fire causes the enemy to undervalue it.

In the Union Army of 1861 there were four kinds of projectiles used in field service, viz : the SOLID or BOUND SHOT, the OANISTER, the SHELL, and the SPHERICAL CASE SHOT. The projectile is attached to a block of wood called a SABOT. For the guns and the 12-pounder howitzer, the cartridge and the projectile are attached to the same sabot, making together a round of fixed ammunition. For 32-pounder and 24-pounder howitzers, the projectile is separate from the charge, and the cartridge is attached to a block of wood called a cartridge block. The CANISTER consists of a tin cylinder, attached to a sabot and filled with tad-iron shot. These shot vary in diameter, and of course in weight, with the calibre and description of the piece. Canisters for guns contain 27 shots each ; those for howitzers contain 48 shots each. They are packed in sawdust in four tiers ; the lower tier rests on a rolled iron plate, which ;s placed on the sabot, and the canister is closed with a sheet-iron cover. The canister takes its designation from that of the piece for which it is prepared.

An 1878 treatise considered the situation when an armed and turbulent mob exists in a large city, the civil authorities are powerless to suppress violence. As a last resort the military force has been duly and properly called upon. Unless protected by barricades it is not probable that the mob will long withstand the fire from the skirmish line. If the mob is not behind barricades the artillery should use canister (canister being less destructive to property than grape, solid shot, or shell, and probably more effective for this purpose at close range). If the enemy is protected by defenses, it may be necessary to use shell and solid shot to dislodge him.

By around the year 1900 Case-shot, or CANISTER, was an artillery projectile for use at close quarters, and consisted of a sheet-iron or tin cylinder filled with bullets varying from an oz. to 1 Ib. in weight, and in number according* to the size of the gun. The cylinder is closed by discs of wood, tin, or iron, its walls are strengthened by loose pieces of iron, and the interstices between the balls are packed with shavings and sawdust. On discharge the canister breaks up at once, and the bullets spread over a wide area, but with a low velocity. For this reason they have little effect beyond 300 yards, even on haru open ground, which is best suited to their action. Case- shot is chiefly used in the close defence of works, or against cavalry, and at sea against a boat attack. At long ranges its place is taken by Shrapnel Shell.

Over time the grape, canister, and spherical case of field artillery lost ground in the field They were more especially formidable and useful when musketry fire was only available up to 200 yards; but they were superseded when the infantry man with his rifle can in some respects do the work better. The Enfield rifle in the hands of the infantry was capable of making a greater proportion of destructive hits between 600 and 1100 yards on a column of men than the artillery with their spherical case.

In the Great War canister had been replaced by shrapnel, which bursts approximately 200 m. in front of the gun when the fuse is set at zero. In canister, the contained bullets have a smaller initial velocity than the case. They richochet on striking. The range of these ricochets depends upon the character of the ground. Solid, level ground, or a gentle downward slope increase their range, whereas snow, sand, wet meadows, ploughed and cultivated land reduce their range. Since the introduction of smokeless powder, the range of canister has decreased, as this powder requires that the projectile close the barrel more tightly than canister is capable of doing. The small
dispersion, the superficial direction, and flat trajectory of its individual bullets made canister very effective against standing targets at short ranges. *

In World War II the Bougainville operation began with initial landings taking place on 1 November 1943 and, ended on 28 December 1943. Marines on Bougainville used a "buckshot" antipersonnel round fired from tanks with deadly effect. Medium tanks, closing on known Japanese positions, acted as bait; as the Japanese swarmed over the tank to emplace a charge in order to destroy it, a companion light tank would fire the "buckshot" round directly at the heavier one. The thumbnail-size projectiles would slaughter the attackers but could not penetrate the armor of the vehicle.

The shock effect of even a single tank in guerrilla warfare was apparent in Vietnam. Lieutenant Colonel Ronald J. Fairfield, Commanding Officer, 1st Battalion, 69th Armor, stated, "The NVA/VC have shown a reluctance to engage tanks where they can be avoided."' A year later, Lieutenant Colonel Paul S. Williams, Jr., while commanding the same battalion, said: "Captured documents and interrogation reports disclose that the enemy is afraid of tanks. We feel what he really fears is the cannister round and its effect. This [feeling] has been justified, to a degree, by the absence of contact when tank and infantry units move together." Obviously, the enemy did fight armored and cavalry units, but usually he either was put in a position where he had to fight or felt that he possessed sufficient strength to defeat the American force.
The effective range of the modern 105 mm canister is out to 500 meters. It is large enough to carry a payload capable of incapacitating an advanced squad of 10 men wearing winter gear. The cartridge is fired from standard United States Government military equipment with rifling typically used for firing 105 mm ammunition. The 105 mm canister has a plastic slip band in order to control the spinning of the projectile. There is no fuze on this round. In a preferred embodiment, the canister contains approximately 800-1000 tungsten balls, which are expelled upon muzzle exit.